There are many kinds of burrs, e.g., burrs at the end of a surface cut by a cutting tool, burrs at the edge of a stamped plate, burrs at the seam of the mold in die casting, beads caused by flame cutting or welding, etc. Hitherto, these burrs were often removed manually. However, in the progress of production techniques, and to increase productivity, the methods of burr removal developed in many ways, including mechanical, chemical or electro-chemical ways.
The primary requisite conditions in deburring are (1) the primary purpose of the initial production process, in which burrs are formed, can not be effected by the deburring operation, (2) the deburring may not alter the physical nature of the material, (3) the deburring may not obstruct the following processes and (4) the deburring process can not damage the surface of the workpiece. These conditions are severe. A water jet blasting machine is offered for removing burrs so as to satisfy these prerequisite conditions. However, in the known blasting machines, the pressure of water used is often as high as 250 kg/sq cm (or 3,500 psi.). The blasting machine thus needs a large capacity pump, which is extremely expensive.
This invention relates to a machine for permitting deburring in a manner so as to satisfy the above requisite conditions, while at the same time providing a machine which is substantially less expensive and permits use of substantially lower water pressures than is conventionally utilized by the above-described wet blasting machines which rely solely on a water jet for effecting burr removal.
More specifically, this invention relates to a blasting machine which uses an abrasive particle-water slurry for blasting so as to effect burr removal, whereby the machine thus permits utilization of a substantially reduced water pressure level, the pressure of the water being reduced to approximately 30 kg/sq cm (450 psi.). The capacity of the pump thus need not be so large. Water blasted from the gun, with abrasive particles mixed therein, is separated from solid particles and reused repeatedly. Water is used in supporting and expelling the abrasive particles. On the other hand, small solid particles existing in the slurry, such as fractures of the abrasive particles or small metal fragments removed by blasting, are removed as much as possible. The water blasts from the gun at substantially constant pressure without pulsation. The consumed abrasive particles are suitably replenished. These conditions are objects achieved by the improved blasting machine of this invention.